Mechanisms controlling the phase and dislocation density in epitaxial silicon films grown from silane below 800 °C

Abstract

We construct a phase diagram for silicon layer growth on (001) Si by hot-wire chemical vapor deposition (HWCVD), for rates from 10 to 150 nm/min and for substrate temperatures from 500 to 800 °C. Our results show that a mixed mono and dihydride surface termination during growth causes polycrystalline growth; some H-free sites are needed for epitaxy. For epitaxial films (T>620 °C), the dislocation density decreases with increasing growth temperature because of reduced O contamination of the surface. The best HWCVD epitaxial layers have dislocation densities of 105 cm−2.

Thickness-dependent defect structure of epitaxial silicon thin films deposited by hot-wire chemical vapor deposition

“…So, for the successful application of these films in solar cells, it is necessary to discover the origin of the polycrystalline defects, and to develop a procedure to significantly decrease their density. However, it is possible that other types of defects, such as dislocations, which have been observed in similar films [11], may have a stronger effect on the efficiency parameters of devices made with these films. It is important to mention that the above discussion just took into consideration the presence of the polycrystalline defects and do not include beneficial effects that increasing the films thickness may have in devices, such as enhanced absorption of the incident solar radiation.…”

Towards Low-cost >15% Efficient Film c-Si Solar Cells: Progress & Challenges

“…[8] To fabricate solar cells, we passivate the silicon with H, [9] grow an i/p amorphous silicon heterojunction and indium tin oxide contact layer. Individual mesas are then lithographically defined and metal grids are deposited.…”

Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

“…[11][12][13] Compared to high temperature CVD epitaxial growth or ultra-high vacuum MBE technique, our approach targets much lower cost. We go here into details about structural properties (stress and defects) of thicker layers, up to 168 nm, of epi-Ge layers on c-Ge and on c-Si substrates, and show that, unlike standard epitaxial techniques, [14][15][16] low TDD and no epitaxial breakdown is achieved in this approach.…”